#include "mystdio.h"


myFILE* my_fopen(const char* path, const char* flag)
{
  int flag1 = 0;
  int iscreate = 0;
  mode_t mode = 0666;
  if(strcmp(flag, "r") == 0)
  {
    flag1 = (O_RDONLY); 
  }
  else if(strcmp(flag, "w") == 0)
  {
    flag1 = (O_WRONLY | O_CREAT | O_TRUNC);
    iscreate = 1;
  }
  else 
  {}

  int fd = 0;
  if(iscreate)
  {
    fd = open(path, flag1, mode); 
  }
  else 
  {
    fd = open(path, flag1);
  }
  
  if(fd < 0)
  {
    return NULL;
  }

  myFILE* fp = (myFILE*)malloc(sizeof(myFILE));
  if(!fp) return NULL;

  fp->fileno = fd;
  fp->flags = FLUSH_LINE;
  
  fp->cap = LINE_SIZE;
  fp->pos = 0;

  return fp;
}

void my_fflush(myFILE* fp)
{
  write(fp->fileno, fp->cache, fp->pos);
  fp->pos = 0;
}

ssize_t my_fwrite(myFILE* fp, const char* data, int len)
{
  // 写入操作的本质是拷贝，如果条件运行，就刷新，否则不做刷新
  memcpy(fp->cache + fp->pos, data, len);
  //write(fp->fileno, data, len);
  fp->pos += len;
  
  if((fp->flags & FLUSH_LINE) && fp->cache[fp->pos - 1] == '\n')
  {
    my_fflush(fp);
  }

  return len;
}

void my_close(myFILE* fp)
{
  my_fflush(fp);
  close(fp->fileno);
  free(fp);
}

